I find if I am having an indigestion or heartburn problem then drinking water makes it much worse....I kind of remember that the reasoning is that the body monitors the acid content of the stomach. If the acid concentration or ph drops then the body releases more acid to compensate.
I find it interesting that you take cider vinegar, which contains acetic acid, if your stomach acid is too high. Bicarbonate of soda I can cope with, as that neutralises acid.
come on sqad think back to matric
pH 2 is 1/100 mol /li
say you dilute by a half so the conc of acid is 1/200 mol/li
relog to get pH again - 2 - 0.3 I make it -2.3
and so the change is 0.3
( the log 10 of the factor of dilution, log 10 of 2 is 0.3 I am sure you remember from O level maff)